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Environmental fate & pathways

Biodegradation in soil

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Link to relevant study record(s)

Description of key information

Only one study was allocated to this endpoint. The study (Klier et al., 1992) was considered relevant to demonstrating fate of biphenyl following chronic spillage to soil. Because biphenyl has been demonstrated to be readily biodegradable, no further testing concerning this endpoint is needed.

Key value for chemical safety assessment

Additional information

In the single available study, biodegradation of biphenyl was examined in combination with phenol in a natural soil/groundwater system obtained from a site historically contaminated with hydrocarbons. At an initial concentration of 1 ppm in the soil/groundwater mixture, DT50 values for mineralization ranged from 5 to 22 days, and monitoring of14CO2evolution indicated ultimate biodegradation of 40-90% after 28 d, depending on the soil used. Biodegradation was enhanced by addition of N and P: DT50 values of 1.5-3.5 d were obtained, whereas monitoring of14CO2evolution indicated ultimate biodegradation of 40-50% after 36 d, depending on the soil used. The study was considered reliable, but should be considered that the combination with phenol may have affected the test results for the individual substances (e.g., via co-metabolism), and although the tests were conducted in closed systems with radiolabeled biphenyl, no mass balance was presented. However, because up to 90% of applied radioactivity was evolved at14CO2, it could be assumed that the test system was suitable for containing the test substance. Because the study involves soil with a history to contamination, including with other substances, it was not used as Key Study for this endpoint, but is still relevant to demonstrating potential for ultimate degradation in soils.

Because biphenyl is demonstrated to be readiliy biodegradable, no additional testing in soil is necessary or required.